(1) Field of the Invention
This invention relates to a method of mounting electronic components on circuit boards employed in electronic equipment such as video, audio, and office automation devices.
(2) Description of the Prior Art
Cost reduction of electronic equipment such as video, audio, and office automation devices is always desirable. One manner of reducing cost may be implemented at the manufacturing level. For example, at the manufacturing level, printed circuit boards are employed and electronic components are mounted on the printed circuit boards.
An exemplary method of mounting electronic components on printed circuit boards is explained below.
FIG. 1 shows a cross-sectional view of an electronic component which is mounted on a circuit board in accordance with the prior art. Before mounting an electronic component, solder 15 is printed on the conductive printed pattern 11a on the insulating board 11. The electronic component 14 is mounted on the board 11 so that the terminal 14a of the component 14 is fitted on the solder 15. Then, by heating the solder 15 to a sufficiently high temperature, the solder 15 melts. After cooling, the electronic component 14 is fixed to the circuit board 11 and the terminal 14a of the component 14 and the conductive printed pattern 11a are electrically connected by solder 15.
However, the above-mentioned mounting method has several problems:
(1) Even in the case which there are few components, a manufacturing process which includes the printing of solder 15 and the addition of heat to melt the solder 15 takes much time.
(2) To add sufficient heat for melting of the solder 15 (generally 220.degree. to 280.degree. degree C.) it is necessary for the material (such as an insulating board 11 and the component 14) to be able to withstand the heat. The use of such materials provides an added expense.
(3) In a low cost printed circuit board, when silver paste is generally used, a special solderable conductive material as a printed pattern 11a and the use of low melting solder are typically required.